Skip to main content

Difference between a constant and readonly variables/fields : (constant vs readonly)



Most of us would have encountered these questions

  • What is the difference between constant and readonly fields?
  • When to use constant and when to use readonly fields?
  • What is the advantage/disadvantage of each?

Constants
  • In C# you can declare a constant like this "const" is a keyword.
    public const string _constStrVar = "I am a static const str val";
  • A constant variable should have value at design time. 
  • All the constant variables are static ie they are shared across all the instances of the class. You dont have to add the keyword "static".
  • Constants are copied to all the dlls where is refereeing the parent class ie even if you change the the original constant value and recompile the parent dll , the other dll will still use the old value. The size of the executable goes up since all these constants are copied to the respective dlls

Read Only 

  • Read only variables are created usually in the constructor of class. there fore it will have values before the constructor of the class exists
    class MyClass
    {
        public readonly string _strReadonly;
        public void MyClass(string strVal)
            {            _strReadonly = strVal;
              }       
            }


        a read only variable will have different values for each object whereas a constant variable will have only one.

        Comments

        Popular posts from this blog

        SCRUM- Who should write a user story

        Traditionally user stories (or requirements) were written by Business analysts. They used to prepare big documents after months of study. It was a herculean task. I used to get such UI/Functional specification documents. I have fixed a lot of bugs because I missed few text in such 1000 + pages document. This is not the only interesting part. Some of the requirements were so weird that I often wondered why I am creating the features which no one is going to use. If I had the option I would have recommended a better option. If the BA’s misunderstood some requirements & customers failed to correct those few words in the epic requirement then we will have a nice situation.
        In the agile world the story is different. Product Owners are primarily responsible for user stories. But can anyone else also contribute? Yes. Definitely yes In actual environment many users write user stories. The first requirement may come from end user. The PO, tech architect, scrum master, BA’s... anyone can upd…

        PDCA & SCRUM (or Agile); Why is it important?

        The PDCA (Plan DO Check Act) cycle was made popular by Dr. W. Edwards Deming. This is a scientific cyclic process which can be used to improve the process (or product). This is cyclic in nature and usually time boxed.

        Plan 
        This is the first stage of the process. During this step the team discusses the objectives, the process and the clear conditions of exit (conditions of acceptance). This stage sets the measurable and achievable goals for the team.

        DO
        Team works together to achieve the objective set in the planning phase. Team works with the set of agreed process.

        Check
        Once the implantation is done team regroups and verifies the output and compares it to the agreed conditions of acceptance decided during the planning phase. The deviation, if any, is noted down.

        ACT
        If any deviation in planned tasks is observed during the Check stage, a root cause analysis is conducted. Team brainstorms and identifies the changes required to prevent such deviations in future. Team also brainstorms idea…

        What are the rules of scrum?

        A relatively new person to scrum asked me this question last day. My answer to that person was yes. But really does the scrum have any rules? Scrum is a framework which helps us in developing software. It has very few rules and apart from those basic rules rest of them are guidelines like best practices.

        Some of the rules 

        The roles of Scrum
        •Scrum Master - http://www.theagileschool.com/2012/03/scrummasters-checklist-roles.html
        •Product Owner
        •Feature TeamThe PDCA cycle (http://www.theagileschool.com/2012/05/pdca-scrum-or-agile-why-is-it-important.html )  frequent communication about risks (daily)
        •Plan – Sprint planning
        •Do – Actual engineering sprint – deliver a potential shippable code
        •Check – Sprint review
        •Act – Retrospective 
        The scrum guide @ http://www.scrum.org/Scrum-Guides will be a good guideline for teams/companies planning to start scrum. If you are following the recommendation in these then you are following scrum.
        Apart from these rest of the ceremonies and artifacts are there…